Modern gas turbines often operate at extremely high temperatures. The effect of temperature on the turbine blades and/or stator vanes can be detrimental to the efficient operation of the turbine and can, in extreme circumstances, lead to distortion, oxidation and possible failure of the blade or vane. In order to overcome this risk, components, like blades or stator vanes, of high temperature turbines may be coated with a thermal barrier coating (TBC).
Often, blades and vanes are designed as single components allowing them to be coated individually to obtain satisfactory coating results. This leads to a higher number of parts to handle and also increased cost. Thus, to reduce time and costs as well as to provide an assembly with a low leakage flow and that is more stable in assembly and operation multiple aerofoils are processed in a single casting. When coating such a casting, using a so called line-of-sight coating approach the quality of the coating in some areas can be poor.
Problems arise in this approach when the aerofoils of the turbine assembly are arranged in such a way that specific regions of one or several aerofoils are covered or blocked by another aerofoil during the coating process. This creates so-called Blind spots where local uncertainty with the coating quality and thickness may occur. This may negatively affect the life and integrity of the component due to excessive temperature for the state of the surface or coating.
It is a first objective of the present invention to provide an advantageous method for manufacturing a turbine assembly, which comprises at least two aerofoils that are arranged adjacent towards each other. A second objective of the invention is to provide a thus manufactured and advantageous turbine assembly for high temperature applications.